Mudskipper fish (Periophthalmus barbarus; pictured) use water bubbles as a 'tongue' to feed on land. The finding hints at how other animals might have evolved tongues as they made the transition from aquatic to terrestrial life.
Krijn Michel at the University of Antwerp in Belgium and his colleagues used high-speed video and X-ray imaging to study the feeding behaviour of various animals. They found that when the mudskipper eats on land, a bubble of water held in its mouth protrudes out and touches food before its jaws close. The fish sucks some of this water back into its mouth as it engulfs the food. The movement of a bone involved in mudskipper feeding resembles that of some animals that feed with tongues on land, the authors say.
This pseudo-tongue allows mudskippers to catch and swallow food items on land, unlike some other aquatic species that must return to water to consume what they capture ashore.
Proc. R. Soc. B http://doi.org/2wr (2015)